Method of treating atherosclerosis with trisubstituted ureas

ABSTRACT

Methods of treating atherosclerosis with trisubstituted ureas, compositions thereof and processes for their preparation.

BACKGROUND OF THE INVENTION

This invention relates to organic compounds useful as pharmaceutical agents. The compounds of the present invention are antiatherosclerotic agents capable of ameliorating atherosclerosis by counteracting the formation or development of atheromatous lesions in the arterial wall of mammals. The invention also relates to the chemical synthesis of the compounds disclosed herein. In addition, the invention pertains to novel pharmaceutical compositions for the utilization of these compounds in the treatment of disease in mammals. Further, the invention contemplates methods for treating atherosclerosis in a manner designed to prevent, arrest, or reverse the course of the disease.

A variety of urea compounds can be found in the literature, for example, in J. Med. Chem. 18, 1024 (1975); U.S. Pat. Nos. 2,688,039; 3,335,142; 3,856,952; 3,903,130; and in West German Offenlegungsschrift No. 29 28 485. The compounds found in the literature are disclosed as being useful herbicides, plant growth regulators, bactericides, pesticides, fungicides, algacides, photographic sensitizers, antihelmintics, sympatholytics and antivirals. Those urea compounds found in Offenlegungsschrift No. 29 28 485 are disclosed as useful in inhibiting lipid absorption. There are, however, no literature references disclosing the use of the trisubstituted ureas of this invention in the treatment of atherosclerosis.

Atherosclerosis is a form of arteriosclerosis characterized by lipid accumulation in and thickening of the arterial walls of both medium and large-sized arteries. Arterial walls are thereby weakened and the elasticity and effective internal size of the artery is decreased. Atherosclerosis is the most common cause of coronary artery disease and is of great medical importance since the occlusion of medium and large-sized arteries diminishes the supply of blood to vital organs such as the heart muscles and the brain. The sequelae to atherosclerosis include ischemic heart disease, heart failure, life-threatening arrythmias, senility and stroke.

The fact that cholesterol is a major component of atherosclerotic lesions or plaques has been known for more than 100 years. Various researchers have studied the role of cholesterol in lesion formation and development and also, more importantly, whether lesion formation can be prevented or lesion development arrested or reversed. Atheromatous lesions have now been shown [Adams, et al., Atherosclerosis, 13, 429 (1974)] to contain a greater quantity of esterified as opposed to unesterified cholesterol than the surrounding undiseased arterial wall. The intracellular esterification of cholesterol with fatty acids is catalyzed by the enzyme "Fatty acyl CoA:cholesterol acyl transferase" or ACAT and the accumulation and storage of cholesterol ester in the arterial wall is associated with increased activity of this enzyme [Hashimoto and Dayton, Atherosclerosis, 28, 447 (1977)]. In addition, cholesterol esters are removed from cells at a slower rate than unesterified cholesterol [Bondjers and Bjorkerud, Atherosclerosis, 15, 273 (1972) and 22, 379 (1975)]. Thus, inhibition of the ACAT enzyme would diminish the rate of cholesterol esterification, decrease the accumulation and storage of cholesterol esters in the arterial wall, and prevent or inhibit the formation and development of atheromatous lesions. The compounds of the present invention are very potent inhibitors of the ACAT enzyme. Thus, these compounds are useful for controlling and reducing the cholesterol ester content of mammalian arterial walls and decreasing the accumulation and storage of cholesterol in the arterial walls of mammals. Further, the compounds of this invention inhibit the formation or development of atherosclerotic lesions in mammals.

The evidence that hyperlipidemia is one of the factors involved in coronary heart disease is very impressive. A most important study carried out in Framingham, Mass. (Gordon and Verter, 1969) in over 5,000 persons for more than 12 years established a correlation between high concentrations of blood cholesterol and increased risk of heart attack. Although the causes of coronary artery disease are multiple, one of the most constant factors has been the elevated concentration of lipids in the blood plasma. A combined elevation of cholesterol and triglycerides has been shown (Carlson and Bottiger, 1972) to carry the highest risk of coronary heart disease. The majority of patients with ischemic heart disease or peripheral vascular disease were found to have hyperlipoproteinemia, involving very low-density and/or low-density lipoproteins (Lewis, et al., 1974).

We have now found that a representative member of this class of compounds can safely and effectively lower serum lipids in warm-blooded animals. Such action on serum lipids is considered to be very useful in the treatment of atherosclerosis. For some time it has been considered desirable to lower serum-lipid levels and to correct lipoprotein imbalance in mammals as a preventive measure against atherosclerosis. The compounds of the present invention do not act by blocking late stages of cholesterol biosynthesis and thus do not produce accumulation of intermediates such as desmosterol, as equally undesirable as cholesterol itself. Compounds with the combination of therapeutically favorable characteristics possessed by those of the present invention can be safely administered to warm-blooded mammals for the treatment of hyperlipidemic and atherosclerotic states found in patients with or prone to heart attacks, to peripheral or cerebral vascular disease, and to stroke.

The compounds of this invention exhibit antiatherosclerotic activity and the invention should not be construed as limited to any particular mechanism of antiatherosclerotic action.

SUMMARY OF THE INVENTION

This invention relates to a method for treating atherosclerosis employing ureas which may be represented by formula I: ##STR1## wherein R₁ and R₂ are different and are independently selected from the group consisting of C₄ -C₁₂ alkyl, C₄ -C₁₂ alkenyl, C₄ -C₁₂ alkynyl, C₄ -C₁₂ cycloalkyl, C₄ -C₁₂ cycloalkylalkyl C₇ -C₁₄ aralkyl, and C₇ -C₁₄ aralkyl in which an aromatic ring bears at least one substituent selected from the group consisting of C₁ -C₁₀ alkyl, C₁ -C₁₀ alkoxy, phenoxy, benzyloxy, methylenedioxy, C₁ -C₄ alkylthio, phenyl, halo, trihalomethyl, adamantyl, C₁ -C₄ carboalkoxy and nitro.

Preferred embodiments of the invention are those in which R₁ is C₇ -C₁₄ aralkyl or substituted C₇ -C₁₄ aralkyl and R₂ is C₄ -C₁₂ alkyl.

Preferred specific embodiments involve 1-benzyl-1-(n-butyl)ureas, for example:

1-benzyl-1-(n-butyl)-3-(3-phenyl)urea

1-benzyl-1-(1,2-diphenylethyl)-3-(phenyl)urea

1-benzyl-1-[1-(3-methoxyphenyl)-2-phenylethyl]-3-(phenyl)urea

1-benzyl-1-[1-(4-benzyloxyphenyl)-2-phenylethyl]-3-(phenyl)urea

1-benzyl-1-[1-(3-methoxyphenyl)-2-phenylethyl]-3-(phenyl)urea

This invention also relates to a method of reducing the cholesterol content of the arterial walls of mammals which comprises administering to said mammal an effective amount of a compound as recited above.

This invention also relates to a method of treating hyperlipidemia in mammals which comprises administering to said mammal an effective amount of a compound as recited above.

This invention further relates to a method of inhibiting atherosclerotic lesion development in mammals which comprises administering to said mammal an effective amount of a compound as recited above.

This invention still further relates to a pharmaceutical composition which comprises an effective antiatherosclerotic amount of a compound as recited above in association with a pharmaceutically acceptable carrier.

Finally, this invention relates to processes for preparing compounds as recited above. One process especially useful for the preparation of trisubstituted ureas involves reacting an arylisocyanate of formula II with a secondary amine of formula III; wherein R₁ and R₂ are as defined above. ##STR2##

A second process for the preparation of ureas involves reacting a compound of formula IV; wherein A and B are leaving groups, which may be the same or different, selected from the group consisting of halo, C₁ -C₄ alkoxy, phenoxy, 4-chlorophenoxy and 4-nitrophenoxy; with a secondary amine of formula III to yield an intermediate of formula V and then reacting the intermediate with an arylamine of formula VI, wherein R₁ and R₂ are as defined above. ##STR3##

A third process for the preparation of these ureas involves reacting a compound of formula IV with an arylamine of formula VI to yield an intermediate of formula VII, wherein B is as defined above and then reacting this intermediate with a secondary amine of formula II. ##STR4##

DETAILED DESCRIPTION OF THE INVENTION

Many of the ureas of this invention are prepared by reacting arylisocyanates with secondary amines. These reactions may be performed in aprotic solvents such as hexane, diethyl ether, toluene, tetrahydrofuran, and the like at temperatures from room temperature or below up to the boiling point of the solvent used. The ureas are isolated by filtration or by evaporating the solvent and they may be purified by recrystallization, absorption chromatography, or distillation under reduced pressure. An example of this process is the reaction of phenylisocyanate with N-benzyl-N-(n-butyl)amine to yield 1-benzyl-1-(n-butyl)-3-(phenyl)urea.

Certain of the ureas of this invention are prepared by reacting activated derivatives of carbonic acid such as phosgene or phenyl chloroformate with secondary amines to yield an intermediate, for instance, a disubstituted carbamyl chloride. This intermediate is in turn reacted with an arylamine to yield the urea. The preparation of the intermediate is conducted in an aprotic solvent such as tetrahydrofuran, toluene, xylene, or the like at temperatures from about room temperature up to the boiling point of the solvent. The intermediate may be isolated by evaporation and purified by distillation if necessary. The intermediate is then reacted with an arylamine in an aprotic solvent such as dimethylacetamide in the presence of a base such as sodium hydride at temperatures from about room up to the boiling point of the solvent used. An example of this process is the reaction of phosgene with N-benzyl-n-butylamine in toluene to yield the intermediate N-benzyl-N-(n-butyl)carbamyl chloride, which is then reacted with aniline in N,N-dimethylacetamide in the presence of sodium hydride to yield 1-benzyl-1-(n-butyl)-3-(phenyl)urea.

Other of the ureas of this invention are prepared by reacting arylamines with activated derivatives of carbonic acid such as phosgene to yield an intermediate, for instance, an arylcarbamyl chloride. This intermediate is then reacted with a secondary amine to yield the urea. The preparation of this intermediate is conducted in an aprotic solvent such as toluene or xylene at temperatures from about room temperature up to the boiling point of the solvent in the presence of a base, for example, N,N-dimethylaniline.

The intermediate is then reacted with a secondary amine in an aprotic solvent such as toluene at temperatures from room temperature or below up to the boiling point of the solvent. An example of this process is the reaction of phosgene with aniline to yield the intermediate N-(phenyl)carbamyl chloride which is then reacted with N-benzyl-n-butylamine to yield 1-benzyl-1-(n-butyl)-3-(phenyl)urea.

The ureas of the present invention are obtained as crystalline solids or distillable liquids. They are characterized by distinct melting or boiling points and unique spectra. They are appreciably soluble in organic solvents but generally less soluble in water.

The preparation and properties of the compounds of this invention will be described in greater detail in conjunction with the specific examples shown below.

A representative compound of the present invention was assayed for a biological activity related to potential use as an antiatherosclerotic agent. The compound was tested in vitro for its ability to inhibit the enzyme fatty acyl CoA:cholesterol acyl transferase (ACAT).

A representative compound was tested for its ability to inhibit ACAT according to the following procedure:

Rat adrenals were homogenized in 0.2 M monobasic potassium phosphate buffer, pH 7.4, and centrifuged at 1000 times gravity for 15 minutes at 5° C. The supernatant, containing the microsomal fraction, served as the source of the cholesterol-esterifying enzyme, fatty acyl CoA:cholesterol acyl transferase (ACAT). A mixture comprising 50 parts of adrenal supernatant, 10 parts of albumin (BSA) (50 mg./ml.), 3 parts of test compound (final concentration 5.2 μg./ml.) and 500 parts of buffer was preincubated at 37° C. for 10 minutes. After treatment with 20 parts of oleoyl CoA (¹⁴ C-0.4 μCi) the mixture was incubated at 37° C. for 10 minutes. A control mixture, omitting the test compound, was prepared and treated in the same manner. The lipids from the incubation mixture were extracted into an organic solvent and separated by thin-layer chromatography. The cholesterol ester fraction was counted in a scintillation counter. This procedure is a modification of that described by Hashimoto, et al., Life Scie., 12 (Part II), 1-12 (1973).

The compound 1-benzyl-1-(n-butyl)-3-(phenyl)urea inhibited ACAT by 82% in this test. This test was actually carried out.

When the compounds are employed for the above utility, they may be combined with one or more pharmaceutically acceptable carriers, e.g., solvents, diluents and the like, and may be administered orally in such forms as tablets, capsules, dispersible powders, granules, or suspensions containing, for examle, from about 0.5 to 5% of suspending agent, syrups containing, for example, from about 10 to 50% sugar, and elixirs containing, for example, from about 20 to 50% ethanol, and the like, or parenterally in the form of sterile injectable solutions or suspensions containing from about 0.5 to 5% suspending agent in an isotonic medium. These pharmaceutical preparations may contain, for example, from about 0.5% up to about 90% of the active ingredient in combination with the carrier, more usually between 5% and 60% by weight.

The antiatherosclerotic effective dosage of active ingredient employed may vary depending on the particular compound employed, the mode of administration and the severity of the condition being treated. However, in general, satisfactory results are obtained when the compounds of the invention are administered at a daily dosage of from about 2 milligrams to about 500 milligrams per kilogram of animal body weight, preferably given in divided doses two to four times a day, or in sustained release form. For most large mammals, the total daily dosage is from about 100 milligrams to about 5,000 milligrams preferably from about 100 milligrams to 2,000 milligrams. Dosage forms suitable for internal use comprise from about 25 to 500 milligrams of the active compound in intimate admixture with a solid or liquid pharmaceutically acceptable carrier. This dosage regimen may be adjusted to provide the optimal therapeutic response. For example, several divided doses may be administered daily or the dose may be proportionally reduced as indicated by the exigencies of the therapeutic situation. A decided practical advantage is that these active compounds may be administered orally as well as by intravenous, intramuscular, or subcutaneous routes if necessary. Solid carriers include starch, lactose, dicalcium phosphate, microcrystalline cellulose, sucrose, and kaolin, while liquid carriers include sterile water, polyethylene glycols, non-ionic surfactants and edible oils such as corn, peanut and sesame oils, as are appropriate to the nature of the active ingredient and the particular form of administration desired. Adjuvants customarily employed in the preparation of pharmaceutical compositions may be advantageously included, such as flavoring agents, coloring agents, preserving agents, and antioxidants eg. vitamin E, ascorbic acid, BHT and BHA.

The preferred pharmaceutical compositions from the stand-point of ease of preparation and administration are solid compositions, particularly tablets and hard-filled or liquid-filled capsules. Oral administration of the compounds is preferred.

These active compounds may also be administered parenterally or intraperitoneally. Solutions or suspensions of these active compounds as a free base or pharmacologically acceptable salt can be prepared in water suitably mixed with a surfactant such as hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, and mixture thereof in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms.

The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases, the form must be sterile and must be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (e.g. glycerol, propylene glycol and liquid polyethylene glycol), suitable mixtures thereof, and vegetable oils.

EXAMPLE 1 1-Benzyl-1-(n-butyl)-3-(phenyl)urea

A solution of 4.89 g. of phenylisocyanate in 100 ml. of hexane was added to a solution of 4.41 g. of N-benzyl-n-butylamine in 150 ml. of hexane and the solution was stirred at room temperature for 2 hours and then evaporated. The residual solid was recrystallized from pentane to yield 1-benzyl-1-(n-butyl)-3-(phenyl)urea.

Table I

The ureas shown in Table I may be prepared from the appropriate arylisocyanates and secondary amines by the method of Example 1 which was actually carried out. Examples 2-26 in Table I are speculative Examples which have not been carried out.

                  TABLE I                                                          ______________________________________                                         Example     Compound                                                           ______________________________________                                         2           1-Benzyl-1-(sec-butyl)-3-(phenyl)urea                              3           1-Benzyl-1-(tert-butyl)-3-(phenyl)urea                             4           1-Benzyl-1-(n-hexyl)-3-(phenyl)urea                                5           1-Benzyl-1-(n-heptyl)-3-(phenyl)urea                               6           1-Benzyl-1-(n-octyl)-3-(phenyl)urea                                7           1-Benzyl-1-(n-nonyl)-3-(phenyl)urea                                8           1-Benzyl-1-(n-undecyl)-3-(phenyl)urea                              9           1-Benzyl-1-(n-tridecyl)-3-(phenyl)urea                             10          1-Benzyl-1-(n-tetradecyl)-3-(phenyl)urea                           11          1-(2-Phenylethyl)-1-(sec-butyl)-3-                                             (phenyl)urea                                                       12          1-(2-Phenylethyl)-1-(n-hexyl)-3-                                               (phenyl)urea                                                       13          1-(2-Phenylethyl)-1-(n-heptyl)-3-                                              (phenyl)urea                                                       14          1-(2-Phenylethyl)-1-(n-octyl)-3-                                               (phenyl)urea                                                       15          1-(2-Phenylethyl)-1-(n-nonyl)-3-                                               (phenyl)urea                                                       16          1-(2-Phenylethyl)-1-(n-decyl)-3-                                               (phenyl)urea                                                       17          1-(2-Phenylethyl)-1-(n-undecyl)-3-                                             (phenyl)urea                                                       18          1-(2-Phenylethyl)-1-(n-tridecyl)-3-                                            (phenyl)urea                                                       19          1-(4-Phenyl-n-butyl)-1-(n-hexyl)-3-                                            (phenyl)urea                                                       20          1-(4-Phenyl-n-butyl)-1-(n-heptyl)-3-                                           (phenyl)urea                                                       21          1-(4-Phenyl-n-butyl)-1-(n-octyl)-3-                                            (phenyl)urea                                                       22          1-(4-Phenyl-n-butyl)-1-(n-nonyl)-3-                                            (phenyl)urea                                                       23          1-(4-Phenyl-n-butyl)-1-(n-decyl)-3-                                            (phenyl)urea                                                       24          1-(4-Phenyl-n-butyl)-1-(n-undecyl)-3-                                          (phenyl)urea                                                       25          1-(4-Phenyl-n-butyl)-1-(n-dodecyl)-3-                                          (phenyl)urea                                                       26          1-Benzyl-1-(1,2-diphenylethyl)-3-                                              (phenyl)urea                                                       ______________________________________                                     

I claim:
 1. A method of treating atherosclerosis, reducing the cholesterol ester content of the arterial wall, inhibiting atherosclerotic lesion development and/or treating hyperlipidemia in a mammal in need of such treatment which comprises administering to said mammal an effective amount of a compound of the formula: ##STR5## wherein R₁ and R₂ are different and are independently selected from the group consisting of C₄ -C₁₂ alkyl, C₄ -C₁₂ alkenyl, C₄ -C₁₂ alkynyl, C₄ -C₁₂ cycloalkyl, C₄ -C₁₂ cycloalkylalkyl, C₇ -C₁₄ aralkyl, and C₇ -C₁₄ aralkyl in which an aromatic ring bears at least one substituent selected from the group consisting of C₁ -C₁₀ alkyl, C₁ -C₁₀ alkoxy, phenoxy, benzyloxy, methylenedioxy, C₁ -C₄ alkylthio, phenyl, halo, trihalomethyl, adamantyl, C₁ -C₄ carboalkoxy, and nitro.
 2. A method as recited in claim 1, wherein R₁ is C₇ -C₁₄ aralkyl and R₂ is C₄ -C₁₂ alkyl.
 3. A method as recited in claim 2, wherein R₁ is benzyl and R₂ is C₄ -C₁₂ alkyl.
 4. A method as recited in claim 1, wherein the compound is 1-benzyl-1-(n-butyl)-3-(phenyl)urea.
 5. A method of treating atherosclerosis in a mammal in need of such treatment which comprises administering to said mammal an antiatherosclerotic amount of a compound as recited in claim
 1. 6. A method of reducing the cholesterol ester content of an arterial wall in a mammal in need of such treatment which comprises administering to said mammal a cholesterol ester-reducing amount of a compound as recited in claim
 1. 7. A method of inhibiting atherosclerotic lesion development in a mammal in need of such treatment which comprises administering to said mammal an atherosclerotic lesion development-inhibiting amount of a compound as recited in claim
 1. 8. A method of treating hyperlipidemia in a mammal in need of such treatment which comprises administering to said mammal an effective lipid-altering amount of a compound as recited in claim
 1. 